A plasma etching device is known as a device used to manufacture semiconductor elements. The plasma etching device includes a stage that holds a substrate (e.g., silicon wafer) in a processing chamber under reduced pressure. As one example of such a stage, Japanese Laid-Open Patent Publication No. 2003-179129 describes an electrostatic chuck device that electrostatically attracts and holds a substrate on a holding base.
FIG. 7 illustrates an electrostatic chuck device 80 in the related art. The electrostatic chuck device 80 includes a base plate 81, an electrostatic chuck (ESC) plate 83, and a focus ring 84. The electrostatic chuck plate 83 is bonded to an upper surface of the base plate 81 by an adhesive layer 82. The focus ring 84 is fixed to an upper surface of the base plate 81 to cover a side surface of the electrostatic chuck plate 83 and a portion of the upper surface of the electrostatic chuck plate 83. The electrostatic chuck plate 83 embeds electrostatic electrodes 85 which attract a substrate W that is an attraction subject. The substrate W is mounted on an attraction surface 83A (here, upper surface) of the electrostatic chuck plate 83 that is exposed from the focus ring 84. Application of DC voltage to the electrostatic electrodes 85 from an external power supply generates electrostatic force. The electrostatic force attracts and holds the substrate W on the attraction surface 83A of the electrostatic chuck plate 83.
When the substrate W, which is attracted to and held on the attraction surface 83A of the electrostatic chuck plate 83, repeatedly undergoes a plasma processing using a highly corrosive processing gas, the plasma irradiation corrodes the attraction surface 83A exposed from a gap between the focus ring 84 and the substrate W. The corroded surface adversely affects the heat transmission property and decreases the attraction force. This shortens the life of the electrostatic chuck device 80.